Viessmann C3TB, Installation And Service Instructions For Contractors

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121
Fault code dis-
played System characteristics Cause Measures
EF Burner in a fault state Flame is lost immediately
after it has built (during
safety time). Check gas supply (gas pressure
and gas flow switch).
Check balanced flue system for
flue gas recirculation.
Check ionisation electrode (replace
if necessary):
■
Distance to burner gauze assem-
bly (see page 78)
■
Electrode soiled
Press reset R .
F0 Burner blocked Internal fault Replace control unit.
F1 Burner in a fault state Flue gas temperature lim-
iter has responded. Check heating system fill level.
Vent the system.
Press reset
R after flue system has
cooled down.
F2 Burner in a fault state Temperature limiter has
responded. Check heating system fill level.
Check circulation pump. Vent the
system. Check temperature limiter
and connecting cables.
Press reset
R .
F3 Burner in a fault state Flame signal is already
present at burner start. Check ionisation electrode and
connecting cable.
Press reset
R .
F7 Burner blocked Short circuit or lead break,
water pressure sensor Check the water pressure sensor
and lead.
F8 Burner in a fault state Fuel valve closes too late. Check gas train. Check both con-
trol paths.
Press reset
R .
F9 Burner in a fault state Fan speed too low during
burner start Check fan, fan connecting cables
and power supply to fan; check fan
control.
Press reset
R .
FA Burner in a fault state Fan idle state not reached Check fan, fan connecting cables
and fan control.
Press reset
R .
FC Burner in a fault state Gas train faulty, faulty
modulation valve control
or flue gas path blocked Check gas train. Check flue sys-
tem.
Press reset
R .
Fd Burner in a fault state and ad-
ditional fault b7 is displayed. Coding card missing. Insert coding card.
Press reset
R .
Replace control unit if fault per-
sists.
Fd Burner in a fault state Burner control unit fault Check ignition electrodes and con-
necting cables. Check whether a
strong interference (EMC) field ex-
ists near the appliance.
Press reset
R .
Replace control unit if fault per-
sists.
Troubleshooting
Fault codes for gas condensing module
(cont.)
5775 636 GB
Diagnosis